chem mc (已知答案,求解)
An iron nail is heated with concentrated sulphuric acid. which folling combinations is correct??
Gas given off Colour of solution formed
A.hydrogen pale green
C.sulphur dioxide pale green
D. sulphur dioxide yellow
請問why is D and why isnot A B C
- sioiengLv 710 years agoFavorite Answer
The answer is: D. sulphur dioxide.... yellow
Iron reacts with common acid to give iron(II) and hydrogen.
Fe(s) + 2H^+(aq) → Fe^2+(aq) + H2(g)
Hydrogen is given off and the solution becomes pale green due to the presence of iron(II) ions.
However, concentrated sulphuric acid, on heating, is a rather strong oxidizing agent. The above reaction thus does not occur. Instead, a redox reaction occurs.
2Fe(s) + 6H2SO4(conc) → Fe2(SO4)3(aq) + 6H2O(l) + 3SO2(g)
Refer to the above equation. Sulphur dioxide gas is given off, and the solution becomes yellow due to the presence of iron(III) ions.
Therefore, the key is D. A, B and C are incorrect.Source(s): sioieng